#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> iint;
typedef pair<ll,ll> llll;
#define ALL(x) (x).begin(),(x).end()
const ll zero = 0;
const ll one = 1;
const ll INF = 9223372036854775807; //10^18
const int inINF = 2147483647; //10^9
const ll MOD = 1000000007; //10^9+7
const ll MOD2 = 998244353;
void Yes() {printf("Yes\n");}
void No() {printf("No\n");}
void YES() {printf("YES\n");}
void NO() {printf("NO\n");}

//dijkstraをする。Gは<to, cost>の配列。dは結果。vは始点。
void dijkstra(vector<vector<llll>> &G, vector<ll> &d, vector<ll> &pre, ll v){
    fill(ALL(d), INF / 2);
    d[v] = 0;

    priority_queue<llll, vector<llll>, greater<llll>> q;
    q.push(make_pair(0, v));
    while(!q.empty()){
        auto p = q.top(); q.pop();
        auto pv = p.second;
        if(d[pv] < p.first) continue; //p.secondへの距離が更新済みならスルー
        for (auto next : G[pv]) {
            if(d[pv] + next.second >= d[next.first]) continue;
            d[next.first] = d[pv] + next.second;
            pre[next.first] = pv;
            q.push(make_pair(d[next.first], next.first));
        }
    }
}

int main(){
    ll N, M;
    cin >> N >> M;
    vector<vector<llll>> G(N);
    map<llll, ll> m;
    vector<ll> u(M), v(M), c(M), d(M);
    for (ll i = 0; i < M; i++) {
        cin >> u[i] >> v[i] >> c[i] >> d[i];
        u[i]--; v[i]--;
        G[u[i]].push_back({v[i], c[i]});
        G[v[i]].push_back({u[i], c[i]});
        m[{u[i], v[i]}] = i;
    }
    vector<ll> dis(N), pre(N);
    dijkstra(G, dis, pre, 0);
    ll tmp = N-1;
    ll ans = dis[N-1];
    for (ll i = 0; i < N; i++) {
        G[i].clear();
    }
    vector<ll> ind;
    while(tmp != 0){
        ll ttmp = pre[tmp];
        bool ch = false;
        if(ttmp < tmp){
            swap(ttmp, tmp);
            ch = true;
        }
        ind.push_back(m[{tmp, ttmp}]);      
        if(ch == false){
            swap(ttmp, tmp);
        }
    }
    int indd = 0;
    sort(ALL(ind));
    for (int i = 0; i < M; i++) {
        if(ind[indd] == i){
            G[u[i]].push_back({v[i], d[i]});
            G[v[i]].push_back({u[i], d[i]});            
            indd++;
        }
        else{
            G[u[i]].push_back({v[i], c[i]});
            G[v[i]].push_back({u[i], c[i]});
        }
    }
    // for (auto vv : m){
    //     printf("%lld %lld %lld\n", vv.first.first, vv.first.second, vv.second);
    // }
    // for (int i = 0; i < N; i++) {
    //     cout << i << " " << pre[i] << endl;
    // }
    // for (int i = 0; i < ind.size(); i++) {
    //     cout << ind[i] << endl;
    // }

    dijkstra(G, dis, pre, N-1);
    ans += dis[0];
    printf("%lld\n", ans);

}